Synthetic detergent cake and process for making the same



United States 3,055,837 SYNTHETIC DETERGENT CAKE AND PROCESS FUR MAKENGTHE SAME George G. Wittwer, 175 Astor Ava, Hawthorne, N.Y. N Drawing.Filed Oct. 8, 1958, Ser. No. 765,936 5 Claims. (Cl. 252-161) Thisinvention relates to a soap-free detergent. More particularly it relatesto a novel solid detergent composition in bar or cake form which hashighly advantageous properties and has equally effective detergentproperties in hard, soft, and salt water. This application is acontinuation-in-part of my copending application Serial No. 603,- 229,filed August 10, 1956, which is a continuation-inpart of applicationSerial No. 369,505, filed July 21, 1953, which in turn is acontinuation-in-part of application Serial No. 221,746, filed April 18,1951, all now abandoned.

Commercial detergents prepared in cake or bar form heretofore haveconsisted principally of soaps derived from animal and vegetable fats asalkali metal salts of higher fatty acids. This conventional type of cakedetergent is readily soluble, producing a rapid and copious lather whenused in soft Water. When used in hard water, however, the soluble fattyacid salts of the soap react with the mineral constituents of the hardwater, producing undesired precipitation of insoluble fatty acid salts,and when used in sea water the phenomenon of curding is produced.Because of these adverse reactions in hard water and sea water,conventional soaps do not lather well in such water, and the fullbenefit of their otherwise good detergent properties is not realized.

Non-soap, or so-called synthetic detergents, are available in powder andother substantially solid form, such as flakes, which are readilysoluble in all types of water and produce satisfactory lathers in hardand sea water. These synthetic detergents include the alkali metal saltsof sulfonated and sulfated aliphatic alcohols, the sulfohated andsulfated aliphatic hydrocarbons, the alkylaryl sulfonic acids,particularly those of the benzene series, the fatty acid amide of methylamino ethyl sulfonic acid, and the alkyl ethers of polyoxyethyleneglycols. These and other sulfuric acid reaction products of highmolecular weight organic compounds are characterized by their highsolubility in Water, their resistance to precipitation by theconstituents of hard water, and their excellent detergent properties,particularly when used in a de-greasing operation.

It is diflicult to form these non-soap synthetic detergents intosatisfactory cake or bar shapes without the use of binding agents havingundesirable properties which impart a gritty feel to the cake andgenerally impair its usefulness as a general purpose detergent. Suchsolid cake forms of these synthetic detergents as can be effected withknown available binding agents also tend to slough off to a high degreeand become softened at a rapid rate upon standing in the presence ofmoisture. They are generally of high solubility and have a higher degreeof hydroscopicity than conventional soap, and, therefore, are subject tothese defects to a higher degree than is conventional soap. Someattempts have been made to modify these defects of the soluble non-soapor synthetic detergents while retaining their good sudsing, lathering,and degreasing properties. One such suggestion is described in U.S.P.2,175,285, where the addition of from 560% of a polyhydric alcohol, suchas glycerine and ethylene glycol partially esterified with a saturatedfatty acid containing 12 or more carbon atoms, is proposed. Othercombinations which have been tried include mixtures of sodium diamylsulfosuccinate, methyl cellulose and boric acid, as in U.S.P. 2,373,863,and a mixture of sodium lauryl sulfire foacetate and thiourea, as inU.S.P. 2,374,544. Such rrnxtures of synthetic detergents have generallybeen compounded with varying percentages of conventional soaps in orderto insure the proper cake formation and its retention in use. To theextent that conventional soaps are contained in the mixture, they aresubject to the same defects as the conventional soaps, themselves, whenused in hard and sea water. They are also subject to more rapiddeterioration in water and moisture than the conventional soapthemselves.

I have now found that a satisfactory all-synthetic detergent cake can bemade having excellent lasting properties and a pleasing feel, with noimpairment to the inherent detergency, sudsing, and lathering propertiesof the synthetic detergent by combining alkylaryl synthetic detergentwith the lauric acid ester of hydroxy ethane sodiurn sulfonate as thebinder. This binder is a relatively insoluble compound having asolubility in the order of 0.2272%, or 2.27 parts per thousand indistilled water at 21 C. The lauric acid ester of hydroxy ethane sodiumsulfonate produces some detergent action, and, when combined with thealkylaryl detergent in accordance with the process described below, notonly effectively binds the alkylaryl detergent into a proper acceptabledetergent cake, but contributes its detergency to the mixture in asynergistic manner to the end that the total available deergency exceedsthe sum of the individual detergencies of the alkylaryl detergent andthe lauric acid ester binder. This lauric acid ester contains nounsaturated hydrocarbon groups, amide linkages or hydroxy radicalscommon to surface active and sudsing agents of similar chemicalstructure which cannot provide effective binding action for thedetergent. It is referred to chemically as sodium lauroyl isethionate,or sodium B-laurylethane sulfonate. It can be prepared byesterific-ation of lauric acid and isethionic acid with subsequentsaponification as follows:

Na.+ OH3(CH2)1 OO OH HOG/11 011280 11 Laurie acid Isethionic acidOHa(UH2)m(H] O CHzOHzSOaNfi Sodium B-laurylethane sulfonate The sodiumB-laurylethane sulfonate may be used as the only binder in the detergentcake, or may be combined with other binders such as the sodiumB-stearylethane sulfonate more specifically described in myabovementioned application Serial No. 603,229. When combined withB-stearyl ethane sulfonate, the sum of the amounts of B-lauryl ethanesulfonate and B-stearyl ethane sulfonate may comprise the minimumpercentage of the binder required for the cake formation as set forthmore particularly below.

The alkylaryl synthetic detergents used in the preparation of mysynthetic detergent cakes are classified as anionic syntheticdetergents, and chemically can be represented generally by the formulawhere R is an alkyl radical or group of alkyl radicals having an averageof at least 10 carbon atoms, and preferably from 12 to 18 carbon atoms,and R is an aryl radical, generally of the benzene series, which may bemodified by additional short-chain alkyl radicals. In commerciallyavailable alkylaryl sulfonate detergents of such composition, theessential alkyl component is generally a straight chain radical havingat least 10 carbon atoms, such as decyl benzene sodium sulfonate. How-Throughout: the specification and claims, Wherever B is used in achemical name or formula, it is intended to designate beta.

ever, the essential alkyl component need not be of uniform length foreach molecule, but may consist of a mixture of different molecules, theaverage carbon content of the alkyl radical being above 10. This isparticularly true in the case of dodecyl benzene. Some commerciallyavailable dodecyl benzene detergents contain uniformly straight chaindodecyl radicals. Others, such as those derived from kerosene fractionsand referred to as keryl benzene detergents, contain a mixture of alkylsubstituted benzene sulfonates wherein the alkyl radical averages CThese are nevertheless classified as dodecyl benzene compounds. Othercompounds of the alkylaryl sulfonate class of detergents includecompounds having modifying alkyl groups on the aryl radical, such asisoalkyls, or alkylated toluenes or poly alkyl benzenes. When suchmodifying alkyl groups are present, or if solubilizing substituentgroups are present in the aryl radical, such as OH, COOH, and NH groups,the alkyl side chain may contain more than the 18 carbon atom limitdesignated for the more common unsubstituted type. In the presence ofsuch substituent groups for the aryl nucleus, the essential alkyl sidechain may contain as many as 20 or more carbons in its radical. In theabsence of such solubilizing groups, the essential alkyl radicalpreferably should contain a number of carbon atoms within the range oflO-18, as higher alkyl chains tend to decrease the solubility of thecompound and impair its detergent properties.

Suitable commercial decyl and dodecyl benzene synthetic detergents, andother alkylaryl synthetic detergents within this class, are referred toin a publication entitled Synthetic Detergents, compiled by J. W.McOutcheon, New York, 1950, at pages 120 and following.

For good detergent properties the synthetic detergent cake shouldcontain at least of the alkylaryl synthetic detergent. This may becompounded with various percentages of the lauric acid ester of hydroxyethane sulfonate sodium salt binder in the range of from 10-90% of thecake, on a dry weight basis. As indicated above, the binder percentagemay be all the lauric acid ester, or it may be a combination of thelauric acid and stearic acid esters in various proportions. Theproportion of the alkylaryl sulfonate detergent accordingly will be inthe range of from 90-10% of the cake, also on a dry weight basis. Theremainder of the composition of the cake may consist of other andsuitable binding materials, such as waxes and/or the B-stearylethanesulfonate mentioned above. It may also comprise fillers or diluents,particularly starches, such as cornstarch, and clays, such as china clayand fullers earth, which add bulk without impairing the detergentproperties or cohesiveness of the synthetic cake. Other materials may beincluded in the remainder of the cake composition for specific purposes.Sodium sulfate, which is often present as a diluent of the commercialalkylaryl synthetic detergent, may be present. Sodium chloride andaluminum sulfate may be included to control the foaming characteristicsand improve the feel of the cake. Tetra sodium pyrophosphate or otheralkaline or acid salts may be included in small amounts for producing adesired pH in the cake. Emollients, such as stearic acid, lanolin,lecithin, glyceryl monostearate,

ethylene glycol stearate, propylene glycol monostearate, may be includedand are generally preferred in percentages up to about 4% when makingcakes for toilet use, since the synthetic alkylaryl detergent ischaracterized by a high degree of fat solubility which has a tendency toproduce a harsh, drying action on the skin. Perfumes, antiseptics,coloring materials, and other special purpose ingredients may also beincluded. Small amounts of soaps (metallic salts of higher fatty acids)may also be included in the remainder of the cake composition forchanging the lathering characteristics of the cake. Collectively, thesematerials constituting the remainder of the composition of the cake maybe referred to as fillers and additives.

Although it is desirable to have varying amounts of the fillers andadditives incorporated into the cake composition for economic reasons,and for the purpose of producing special effects, satisfactory cakeshaving excellent detergent properties and good lasting properties can bemade from combinations of the two essential components, that is, thesynthetic detergent and the lauric acid ester binder, within the statedlimits where the combination of the amounts of detergent and binderconstitute 100% of the cake composition Without the inclusion of anyfillers or additives. Where fillers and additives are included, thecombined proportions of the detergent and lauric acid ester binder will,of course, be less than 100%, and may be as little as 20%. Such a cakemay include any one or all of the possible additives and fillers namedabove, or other materials commonly utilized in the compounding ofdetergent cakes in whatever proportions are needed to produce thedesired effect.

It is believed that the relatively insoluble lauric acid ester binder ofthis invention becomes completely dispersed by the synthetic detergentduring use of the detergent cake in washing operations. There is noprecipitate or insoluble residue apparent such as is encountered whenusing conventional soaps in hard water, nor is there any excessivewasting away of the cake under moist conditions, such as to causesliming and consequent loss of the detergent material. Apparently lauricacid ester binder substantially reduces or eliminates the tendency ofthe more soluble components of the detergent cake to dissolveselectively. This action permits of the use of large amounts of inertfiller materials, such as those mentioned above, and sodium sulfate andsodium chloride in the cake without danger of adversely affecting itswash-stand life. Ordinarily, salts such as sodium sulfate and sodiumchloride, when used as fiiller materials in a detergent cake, areselectively dissolved out in use and contribute to the sliming anddeterioration of the detergent cake.

The foaming, lathering, and general detergency properties of a syntheticdetergent cake made in accordance with the process hereof are good, andare independent of the type of water and the degree of its hardness. Inthe case of hard water, which contains varying proportions of calciumand magnesium compounds as a measure of the degree of hardness, it isnot necessary to vary the composition of this detergent cake toaccommodate higher degrees of hardness. The same cake can be usedequally Well With water of any degree of hardness. In the case of sea orsalt water, the performance of a synthetic detergent cake made inaccordance with the process hereof is superior to that of standard saltwater soaps.

In preparing my synthetic detergent cakes containing the sodiumB-laurylethane sulfonate binder and the sodium alkaryl sulfonatedetergent, it has been found that the ingredients must be meltedtogether in the mixing process at a fairly high temperature in order toinsure that a homogeneous mixture of the ingredients in fusedcombination shall be obtained. Otherwise, the mixture will not besatisfactory and the finished cake Will not be smooth. The cakesproduced from a mixture of the ingredients which has not been properlyfused together will be gritty and sandy, and in use the lastability anduniform dissolution of the binder and detergent will be affected. Inorder to effect the necessary homogeneous mixing and fusion of theingredients, I first prepare a mixture of the sodium alkaryl sulfonatedetergent, the sodium B-laurylethane sulfonate binder in the solidstate, and submit this mixture to a roller mixing operation. Additives,such as alkaline or acid salts which may be added in the solid state,are also incorporated into this dry mix. I then place this mixture in arotary blade mixer equipped with a steam jacket or other suitable meansof heating. Water is added to the mixture in the rotary mixer in anamount of from 15-20% by weight, in order to effect blending of theingredients. The temperature is raised to from C. and maintained at thatlevel during the mixing of the resulting slurry. The mixing is continuedat the 5. elevated temperatures until a homogeneous mass has beenformed. During this mixing procedure the relatively insoluble sodiumB-laurylethane sulfonate binder becomes fused with the more solublealkaryl detergent and the additives, and the water which has been addedfor proper blending is slowly reduced by evaporation. Vigorous agitationof the rotary blade mixer should be continued during the heating andmixing process, and the temperature level and agitation should bemaintained until the water content has been reduced to a minimumdetermined by the hydroscopicity of the detergent ingredients andgenerally not over is retained.

Coloring materials, perfumes, and other such additives soluble in watermay be incorporated by mixing the coloring agent or such other additivewith the water which is added for blending purposes in the mixingoperation of the rotary blade mixer. Also, if starch is added as thefilled or diluent, it may be pre-mixed with heated Water to which alkalimay have been added for the purpose of gelatinizing the starch and thatmixture used as the blending water for the binder and detergent.

When the mass has been thoroughly mixed and the water evaporated to theminimum level, the mixture is transferred to a soap plodder forextrusion under pressure into large bars. Smaller cakes can be made fromthe bars by pressure molding of the latter.

The following examples will serve to further illustrate representativecompositions of my new synthetic detergent cake. The process of mixingand fusing the binder and detergent described above is used in thecompounding of each of the compositions set forth in the tablescontaining the illustrative examples, it being understood that duringthe compounding, in addition to the parts of the ingredients enumeratedin the tables, water in the amount of from -20% has been added duringthe mixing procedure, and has been evaporated down to the minimum ofabout 5% While fusion of the componentshas been effected during thedrying stage. Since the parts given in the tables are on a dry weightbasis, the amount of water in the order of not over 5% retained in thecake is not included.

TABLE OF COMPOSITIONS I Component Dry Weight Parts Example No 1 2 3 4 5Na B-lauryl ethane sulfonate 65 35 104 156 113. 75 Na B-stearyl ethanesulfonate 30 113. 75 Na dodecyl benzene sulfonate 455 455 403 286.00 Nakeryl benzene sulfonate 351 Corn Starch 104 104 117 117 110. 50Tetra-Na-pyrophosphate 13 13 13 13 13. 00 Aluminum sulfate 13 13 13 1313.00

Total Dry Weight Parts 650 650 650 650 650.00

TABLE OF COMPOSITIONS II Component Dry Weight Parts Example No 6 7 8 910 Na B-lauryl ethane sulfonate Na B-stearyl ethane sulfonate- Nadodecyl benzene sulfonate. Na decyl benzene sulfonate" Na lauryl sulfate19 Corn starch 455 Tetra Na pyrophosphate- 13.0 13 13.0 13 13 Aluminumsulfate 13.0 13.0 13 13 Total Dry Weight Parts 650.0 650 650.0 650 650TABLE OF COMPOSITIONS III Dry Weight Parts Component Example N0 11 12 1314 15 Na B-lauryl ethane sulfonate 260 113. 75 37. 5 130 60 Na.B-stearyl ethane sulfonate 113. 75 37. 5 130 N a dodeeyl benzenesulfonate..- 130 116.00 299.0 260 130 Na lauryl sulfate 130 287. 00 130.O Corn starch 117 120.0 117 364 TetraN a py-rophosphat 13 13.00 13. 0 1313 Aluminum sulfate 13.00 13.0 13

Total Dry Weight Parts 650 650.00 650.0 650 650 TABLE OF COMPOSITIONS IVDry Weight Parts Component Example N0 16 17 18 19 20 21 Na B-laurylethane sulfonate--- 325 24 42 36 48 54 Na dodecyl benzene sulfonate 32536 18 24 12 6 Total Parts 650 60 60 60 60 60 TABLE OF COMPOSITIONS V Asstated above, the lauric acid ester binder prevents the selectivedissolution of the more soluble components of the detergent cake, andparticularly the alkylaryl sulfonate detergent. It has also beendiscovered that the solubility of the sodium B-lauryl ethane sulfonatebinder is unexpectedly increased when combined according to the processof this application with the alkylaryl sulfonate detergent. Thefollowing table shows the multiple by which the solubility of the sodiumB-lauryl ethane su1- fonate is increased by addition of the selectedincrements of the alkylaryl detergent. All determinations are at 21 C.The detergent in the test cakes is sodium dodecylbenzene sulfonate. Thebinder is sodium B-lauryl ethane sulfonate. The dissolved binder wasdetermined as cocoanut free fatty acids -(FFA). The molecular ratiofactor of 1.60 converts the cocoanut free fatty acids parts per hundredto sodium B-lauryl ethane sulfonate parts per hundred. The dry weightpercentages of the binder and detergent in the test cakes range from28.6% to 61.5% for the detergent, and from 38.5% to 71.4% for thebinder. Since the test cakes contain only binder and detergent the dryWeights of the respective components can be derived from the solutionpercentages given in the table.

TABLE VI Binder Solubility Increase Deter- Dissolved Dissolved BinderCake No. Binder, gent, H O, FFA, Binder, Solubility Percent PercentPercent Percent Percent Increase Multiple highly insoluble binder issolubilized by the detergent and dispersed during use of the cake inwashing operations, and the highly soluble detergent is therebydischarged with the binder, so as effectively to prevent selectivedissolution of the detergent.

Having thus described my invention, what I claim as new and useful anddesire to secure by Letters Patent is:

l. A solid detergent bar consisting essentially of a homogeneous mixtureof a compound taken from the class consisting of sodiumlaurylisethionate and mixtures of sodium lauryl isethionate with sodiumstearyl isethionate, with an alkyl aryl sulfonate having detergentproperties, the alkyl radical of said sulfonate averaging at least 10carbon atoms, said sulfonate comprising 10% to 90% of said bar on a dryweight basis and said compound comprises 90% to 10% of said bar on a dryweight basis.

2. A solid detergent bar according to claim 1 wherein said compound andsaid sulfonate together comprise at least 20% of said bar on a dryweight basis.

3. A solid detergent bar according to claim 1 wherein said sulfonate istaken from the class consisting of dodecyl benzene sodium sulfonate,decyl benzene sodium sulfonate and keryl benzene sodium sulfonate.

4. A solid detergent bar according to claim 1 wherein said compound iscomposed of 50% sodium lauryl isethionate and 50% sodium stearylisethionate by weight.

5. A method of making a solid detergent cake which comprises mixing acompound taken from the class consisting of sodium lauryl isethionateand mixtures of sodium lauryl isethionate with sodium stearylisethionate, with an alkyl aryl sulfonate detergent having an averagealkyl radical length of at least 10 carbon atoms, in such amounts as toproduce a mixture containing 1090% of said detergent by dry weight and9010% of said iscthionate by ry weight, adding 15-20% by weight ofwater, heating the slurry thus produced to 80100 C., agitating saidslurry until a homogeneous fused mixture is achieved, continuing theheating of said mixture until the water content has been reduced to notmore than about 5% and forming the resultant fused mixture into bars.

References Cited in the file of this patent UNITED STATES PATENTS Re.23,823 Molteni et a1 May 4, 1954 2,156,996 Martin May 2, 1939 2,175,285Duncan Oct. 10, 1939 2,617,772 Keenan Nov. 11, 1952 2,643,229 WaltersJune 23, 1953 2,653,913 Van Dijick Sept. 29, 1953 2,678,921 Turck May18, 1954 2,734,870 Lewis Feb. 14, 1956 2,781,321 Mayhew et a1 Feb. 12,1957 2,894,912 Geitz July 14, 1959

1. A SOLID DETERGENT BAR CONSISTING ESSENTIALLY OF A HOMOGENOUS MIXTUREOF A COMPOUND TAKEN FROM THE CLASS CONSISTING OF SODIUMLAURYLISETHIONATE AND MIXTURE OF SODIUM LAURYL ISETHIONATE WITH SODIUMSTEARYL ISETHIONATE, WITH AN ALKYL ARYL SULFONATE HAVING DETERGENTPROPERTIES, THE ALKYL RADICAL OF SAID SULFONATE AVERAGING AT LEAST 10CARBON ATOMS, SAID SULFONATE COMOPRISING 10% TO 90% OF SAID BAR ON A DRYWEIGHT BASIS AND SAID COMPOUND COMPRISES 90% TO 10% OF SAID BAR ON A DRYWEIGHT BASIS.